Resistor wrapping machine



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RESI STOR WRAPPING MACHINE Filed Sept. 20. 1966 Sheet /6 0f 17 March 4, 1969 B. A. BERGER RESISTOR WRAPPING MACHINE Sheet of 17 Filed Sept. 20. 1966 INVENT R BY w r0 PATENT AGENT United States Patent Oflice 3,430,324 Patented Mar. 4, 1969 3,430,324 RESISTOR WRAPPING MACHINE Bernard A. Berger, Montreal, Quebec, Canada, assignor to Northern Electric Company Limited, Montreal, Quebec, Canada Filed Sept. 20, 1966, Ser. No. 580,755 U.S. Cl. 29-203 22 Claims Int. Cl. H010 17/00; B31f 13/00 ABSTRACT OF THE DISCLOSURE An apparatus for wrapping components having fiat metal cores, such as electrical resistors, with a blank of insulating material. An indexing turret having component holding fixtures is surrounded by work stations, one of which is provided with a component feeding device, which, after each index of the turret, automatically loads a component into one of the fixtures with the core projecting radially outward from the turret. At another of the work stations, a wrapping device is provided to receive the core of each component on each indexing, and the wrapping device is simultaneously fed with a heated blank which is then folded about the core before the next indexing of the turret.

This invention relates to a component wrapping apparatus, and more particularly, to a machine for wrapping the fiat metal cores of electrical components, such as certain types of resistors, with a blank insulating material such as sheet phenolized asbestos.

Known operations of production of electrical components having flat metal cores with terminals extending from one end, such as certain types of resistors, have been relatively slow and involved considerable manual labour. Due to the fact the sheet phenolized asbestos is very brittle when at normal room temperatures, it must be heated prior to folding it around the flat plate portion of the core to avoid fracturing of the phenolized asbestos along the fold lines of the blanks. However, because the phenolized asbestos blanks with the sealing adhesive thereon become very sticky when heated, in one known type of wrapping machine, which was designed to partially automate the wrapping operation, the blanks are fed from a stack in a feed hopper means to a transfer member, and after a core has been placed on top of blank, heat is applied to soften the blank prior to folding. In such a machine complete and thorough heating of the blank under the core may not be satisfactorily accomplished so that fractureless folds are not always accomplished.

In the manufacture of resistors of the above-described type, after an initial wrap is applied to the bare flat metal core the resistor wire is wound around the initial wrap and the core is then wrapped with either a final wrapping blank or is wrapped with a secondary blank in preparation for the application of a second winding which may be followed by one or more additional wrappings and windings before the final wrapping blank is applied. Each wrapping applied after the first must be applied, therefore, to a thicker core than the previous wrapping because of the buildup of windings and wrappings.

In known machines having forming elements which engage the blank and fold it over the core, it has been necessary to make adjustments when changing from an initial wrapping operation to a subsequent wrapping on the same core to compensate for the change in size. Since'if is often necessary to run through small batches of resistors having different values or to interrupt a long run of resistors having one value to supply a few resistors of a different rating which are urgently needed, excessive adjustments each time it is necessary to change from an initial wrapping to a subsequent wrapping, or vice versa, are time consuming and are very undesirable.

It is an object of the present invention to provide a resistor wrapping machine, which will produce a high quality component and yet may operate substantially unattended. It is a further object to provide a machine which may fold onto the resistor core any one of a series of subsequent wrappings for the core without time consuming adjustments of the machine being necessary when changing from one wrapping to another.

According to the present invention, there is provided an indexing turret having thereon a plurality of component holding fixtures each arranged to hold one of the components by its terminals with the plate portion of the component projecting radially outward from the turret. A plurality of work stations are provided around the turret and a component feed means is arranged to load one component at a time from exteriorly of the turret into one each of the holding fixtures indexed to the component feed means at one work station. At another work station, a wrapping means adjacent the turret is arranged to receive the plate portion of the component held by each holding fixture indexed thereto. A wrapping blank feed means is provided for supplying one wrapping blank at a time to said wrapping station, and the wrapping means has actuated folding members for enclosing the plate portion of each component with one of the wrapping blanks.

Thus, each wrapping blank may be individually heated en route to the wrapping means, and this is preferably done by sliding the wrapping blanks, one after the other, along a feed path, and providing a heating means therealong.

In a specific embodiment of the invention, the wrapping means includes a. table member having one side adjacent the turret and a blank supporting upper surface. The table member defines a plate portion receiving cavity extending down from its upper surface and having one end open at the side adjacent the turret. A platform member is contained in the cavity for vertical reciprocation and is biased to a raised position with a flat top surface thereof flush with the upper surface of the table member for supporting, in conjunction with the table member, one of the blanks. A plunger means is provided above the cavity for pushing flatwise downward into the cavity the plate portion of each component held in a holding fixture indexed to the wrapping means, and the platform is movable to a lowered position under the plate portion to thereby bend one of the blanks sandwiched between the plate portion and the top of the platform into a U-shaped configuration consisting of a central portion between the plate portion and the top surface and leg portions extending upward beside opposite sides of the cavity. Latch means is provided for locking the platform member in its lowered position, and a distance above the top surface of the platform member in its lowered position, a side former element is movable into the cavity for bending one leg portion of the U- shaped configuration of the blank over to an acute angle over the plate portion. The latch means is then releasable to permit the platform member to travel upwards towards its raised position so that the bent over leg portion of the blank is bent sharply over and onto the plate portion by being forced against the former element. Because the platform member with the plate portion of the core and the partially folded blank therebetween is pushed to a lowered position a distance below the former element, it makes no difference whether there is one or more wraps already on the core. It is the upward travel of the platform that brings the blank being applied into engagement with former element and this folds the leg portion of the blank over against the core. Moreover, once the upward movement of the platform member stops due to engagement with the former element the upper surface of the core is then automatically properly located for a folding action by the second former element.

In the drawings, which show one embodiment of the apparatus according to the present invention, by way of example:

FIGURE 1 is a semischematic plan view of the machine or apparatus according to the invention;

FIGURE 2 is a side view of a resistor core prior to any operations of the apparatus of FIGURE 1;

FIGURE 3 is a view similar to FIGURE 2, but after the core has been notched in the apparatus shown in FIGURE FIGURE 4 is a view similar to FIGURE 3 but showing the core after a first wrapping of insulating material has been applied by the apparatus of FIGURE 1;

FIGURE 5 is a view similar to FIGURE 4 but after a winding of resistance wire has been formed over the first pp FIGURE 6 is a view similar to FIGURE 5 but after a last wrapping of insulating material has been applied by the apparatus of FIGURE 1;

FIGURE 7 is a plan view of a blank of insulating material which is formed by the apparatus of the present invention and then applied by the apparatus as the first wrapping to the core shown in FIGURE 3 to provide the wrapped core shown in FIGURE 4;

FIGURE 8 is a plan view of a blank of insulating material used to form the last wrap to the component as shown in FIGURE 5 to produce the component shown in FIGURE 6;

FIGURE 9 is a plan view of a core storage rack and dispensing means for automatically feeding cores to be Wrapped;

FIGURE 10 is a side view of the rack and dispensing means shown in FIGURE 9;

FIGURE 11 is a plan view of transfer means for delivering cores from the dispensing means shown in FIGURES 9 and 10 to the turret;

FIGURE 12 is an end view of the core transfer means shown in FIGURE 11;

FIGURE 13 is a cross-sectional view through a blanking press for cutting wrapping blanks;

FIGURE 14- is a partial plan view of conveyor means for transferring wrapping blanks from the blanking press shown in FIGURE 13 with portions broken away for the sake of clarity;

FIGURE 15 is a sectional view of the conveyor means shown in FIGURE 14 taken along the line XV-XV;

FIGURE 16 is a plan view of a conveyor means providing an oven feeder for transferring wrapping blanks through an oven from the conveyor means shown in FIGURE 14 to a wrapping station;

FIGURE 17 is a side elevation view of the conveyor means shown in FIGURE 16;

FIGURE 18 is a plan view of a transfer turret and wrapping station in the apparatus of the present invention on a larger scale than FIGURE 1;

FIGURE 19 is an elevational sectional view through the transfer turret on a still larger scale than FIGURE 18 and showing one core holding fixture in cross section;

FIGURE 20 is a plan view of one of the holding fixtures shown in FIGURE 19;

FIGURE 21 is a plan view of a combined holding fixture unloading and holding fixture load assisting mechanism;

FIGURE 22 is an elevational view of the mechanism shown in FIGURE 21;

FIGURE 23 is a side view of the wrapping mechanism in the apparatus of the present invention;

FIGURE 24 is a sectional view of the mechanism in FIGURE 2 taken along the line XXIV-XXIV.

FIGURES 25 to 29 are views similar to FIGURE 24, but with parts removed for the sake of clarity, and showing locations of certain elements of the wrapping mechanism during different stages of the wrapping process of a core.

Referring first to FIGURES 2 to 8, and particularly FIGURE 2, the resistor wrapping and winding process is carried out on a core 40 shown in FIGURE 2. The core 40 includes a flat sheet metal body portion 41 having two longitudinal slots 42 and 43 extending in from one end to provide two outside tongues 44 and 45 and a central tongue 46. The tongues 44 and 45 and 46 are embedded in a transversely extending dielectric head 47. Formed integrally with central tongue 46 is a central terminal 49 projecting from the opposite side of dielectric head 47 in the same plane as body portion 41. Formed integrally with outside tongues 44 and 45 are terminals 50 and 51 respectively which project from the opposite side of said head as body portion 40 and are also in the same plane as body portion 40. The terminals 50 and 51 are joined by a cross bar 53 so that the terminals 50 and 51 at the end of the terminals opposite the dielectric head 47 and the cross bar form a U-shaped terminal configuration in the same plane as the body 40 but on the opposite side of the dielectric head 47. The cross bar 53 extends slightly past the terminals 50 and 51 to provide a pair of lateral lugs 54 and 55 extending from the outside of the terminals 50 and 51. As will become apparent below the cross bar 53 and lateral lugs 54 and 55 are used for holding and supporting the resistor during the wrapping operations, and the cross bar and lugs are removed on completion of the manufacture of the resistor so that the outer end of the terminals are free.

In FIGURE 1 of the drawings, the reference character 60 generally denotes the automatic resistor wrapping machine of the present invention. Along one side of the machine 60 there is situated a core storage rack 61 which is adapted to hold a plurality of cores 40, such as the one shown in FIGURE 2, and feeding means 62 is provided to deliver the cores one at a time to a notching machine 63. In the notching machine 63, the core is notched as at 64 in FIGURE 3 to sever either one or both of tongues 44 and 45 to isolate one or both of the outer 50 and 51 from body portion 41 of the core. In the example shown in FIGURE 3, terminal 51 is isolated from body portion 41 by notch 64 and this terminal becomes isolated from terminal 50 also, of course, when cross bar 53 is cut from the terminals in a later operation. After the core has been notched it is pushed into a holding fixture 65 on a transfer turret 66.

The turret 66 has a plurality of identical holding fixtures 65 equally spaced about the periphery thereof, and the turret is arranged to index each holding fixture around to the various stations outside the periphery of the turret, each indexing being equal, of course, to the angular spacing of the holding fixture. Thus, after each indexing of turret 66, an empty holding fixture is situated at a loading station 67 adjacent to the notching machine 63 for reception of a notched core 40a such as the one shown in FIGURE 4. Each holding fixture 65 holds the core 40a by the cross bar 53 with body portion 41 of the core projecting radially outward from the periphery of the turret 66.

The turret 66 shown in FIGURE 1 has six holding fixtures 65, by way of example, and no work is done on the core after the first indexing from the loading station 67 in the direction of arrow 79. However, at the next indexing the core enters a preheat station 68 where the body portion 41 has heat applied to it prior to entering the wrapping station 70 during the next indexing so that the metal body portion does not have a cooling effect on the wrapping.

As each core is being forwarded to wrapping station 70 in the manner discussed above, a wrapping blank 71, which is shown in FIGURE 7, is simultaneously prepared and forwarded to the wrapping station 70. The wrapping blank 71, which is formed of insulating material such as phenolized asbestos, is preferably prepared from a continuous strip 69 of material in a supply roll 72. The strip is fed to a blanking press 73 by a conveyor 74 which carries the strip under a heating device 75. At the blanking press 73 the blanks 71 are stamped from the strip, each blank 71 being then transferred one at a time along a conveyor 76 which extends under the blanking press 73 at one end and feeds each blank 71 to an oven conveyor or feeder 77 at the other end. The oven feeder 77 passes each blank 71 through an oven 78 and then delivers the heated and thus sticky and softened blank 71 to the wrapping station.

At the wrapping station 70, each notched core 40a is wrapped with one of the blanks 71, the blank 71 being folded substantially along longitudinal lines 80, 80 and as the blank 71 is shorter than body portion 41 and is provided with a pair of rectangular notches at one end, the end of the body portion 41 remote from dielectric head 47 and the tongues 44 and 45 are left exposed as is shown in FIGURE 4. After the wrapping operation at the wrapping station 70 each wrapped core 401) is indexed to a sealing station 81 at which the wrapped core 41b is simply pressed to insure that the overlapping portions of the wrapping are sealed to each other and that the wrapping is stuck to the body portion 41 of the core 40b. Next the core with the wrapping thereon is indexed to a discharge station 82 where the wrapped core 40b is ejected into a discharge chute 83. From discharge chute 83 the wrapped core 40b slides onto a conveyor 84 which carries the wrapped core 40b from machine 60 to another machine or a storage container, such as a tote box, for example.

After the wrapped cores 40b are discharged one at a time from the machine 60 of the present invention, they are delivered to a working machine (not shown) where resistance wires 86 are wound about the wrapping and have their ends welded, for example, to the exposed outer end of body portion 41 and exposed tongue 45 which is integral with terminal 51 and isolated from body portion 41, whereby wound core 400 shown in FIGURE 5 is produced. The wound cores 400 are then placed in rack 61 to be again fed through the machine 60. The second time through machine 60, the cores have another wrapping blank 71 applied thereto in preparation for yet another winding of resistance wire or the cores have a final wrapping blank 87, which is shown in FIGURE 8, applied thereto. If a second blank 71 is being applied, the operation is the same as that described above, except that notching machine 63 is not operated since the necessary notching is completed the first time through, nor is the preheat station 68 operated as the second wrapping blank 71 is not exposed to the bare metal body portion 41. Also, if the second wrap is the operation of applying wrapping blank 87, the notching machine 63 and preheat station 68 are left inoperative, and it is necessary, of course, to change the punch and die of blanking machine 73 so that a blank of the shape shown in FIG- URE 8 is punched out and forwarded by conveyor 76 and feeder 77 to wrapping station 70.

As shown in FIGURES 6 and 8, the wrapping blank 87 is nearly as long as body portion 41 and has no notches so that it covers the body portion and the other wrappings and windings thereon. Moreover, the blank 87 has an end flap 88, which is folded over the core under the main portion of the blank so as to completely close in the resistor below the dielectric head 47 when the final wrap is applied. Although the wrapping blank 87 is of a different configuration than the wrapping blank 71 and wound core 40c is bulkier than the notched core 40a, no changes to the mechanism at the wrapping station 70 are necessary for reasons which will become apparent from the more detailed description of the wrapping station given below.

As is indicated above, the storage rack 61 is provided at one side of machine 60, and reference is now made to FIGURES 9 and 10 which show the rack 61 together with a dispensing means 90 in more detail. The rack 61 includes a pair of horizontal rails 91, 91 between which cores 40 or wound cores 40c are held. The rails 91, 91 are spaced a distance slightly greater than the total length of cross bar 53 including laterally projecting lugs 54 and 55, but each is provided with an inturned bottom flange 92 extending substantially the lengh of the rail. The 0pposed flanges 92, 92 on the two rails project inwardly only a distance to carry lugs 54, 5S and are spaced a distance greater than terminals 50 and 51 so that the cores may be freely suspended between the rails by lugs 54 and 55 resting on the flanges 91, 91. The dielectric heads 47 and main body portion 41 hang well below the rails 91, 91 as shown in FIGURE 10.

The pairs of rails 91, 91 which are connected at their upper edges by one or more cross-members 94, are carried well above the level of turret 66, the rails being supported at one end by support member 93 which is secured to one of the rails by screws 95. At the other end, namely the dispensing end of the rails, the rails 91, 91 are supported on a table 96, which also carries dispensing means 90, the rails being connected by angles 98, 98 to a vertical plate 97 which extends transversely relative to the rails and is secured to the table 96.

The rack 61 and dispensing means 90 are provided with a biasing means arranged to engage the last core 40 in the rack and to force all of the cores together and towards the dispensing end. The biasing means 100 includes an additional rail 101 which extends along beside the outside of one of the rails 91, 91 the rail 101 being connected at opposite ends to, but spaced from the adjacent rail 91 by brackets 102 and 103. A carriage 104 is slidably mounted on rail 101, the carriage having a rail receiving channel 105 extending therethrough, whereby the carriage 104 can glide substantially from one end to the other of said rails 91, 91. A flexible chain or cable 106 is connected at one end to a small bracket 107 fixed to the carriage. The cable passes around a first pulley 110 mounted on a vertical spindle 111 secured to table 96 by a bracket 112, the cable thus changing direction passes over a second pulley 113 mounted on a horizontal spindle 114 carried by bracket 112. The depending end of the cable 106 hanging from pulley 113 carries a weight 115 suspended in vertical tubular protector member 116. Thus due to the hanging weight 115 the carriage is always biased to the dispensing end of the rails.

To a downwardly extending flange 117 formed on carriage 104, and'arm 120 is slidably connected by screw member 121, 121 received in slots in arm 120 and threaded into flange 117. The arm 120, when in its core engaging position, has an inner end extending under rails 91, 91 and is provided at its inner end under the rails with a projection 122 facing the dispensing end of the rails. The projection 122 is arranged to engage the dielectric head 47 of the last core 40 on the rack, since the dielectric heads 47 are the thickest portion of the cores, and the biasing force applied by weight 115 pushes the dielectric heads of all of the cores on the rack into tight engagement as the biasing force is transferred through the heads of the cores to push the core at the extreme dispensing end of the rails into engagement with a stop member 123. The arm 120 has a handle portion 124 formed on its end opposite projection 122, and the handle portion 124 may be readily grasped to slide the carriage away from the dispensing end against the biasing of weight and to also pull the inner end for sliding the arm out from under the rails.

As will be described in more detail below, the dispensing means 90 is arranged to pick one core at a time from the dispensing end of the rails provided that the 

